I am not an Associate Professor of Theology but my understanding is that God was, is, and always will be. He is without creation. Jesus, the second person in the Holy Trinity, is God and has all the nature of God so Christ is also without creation.
Did God the Father send the Spirit to Mary so that she could bear the Son of God? Yes. By Mary’s fiat, God was Incarnate: God become (the perfect) Man.
Is the Holy Spirit God? Yes but God did NOT create God. The Father, Son, and Spirit all have the same divine nature. If we tried to describe how God Incarnated, we’d fall short of an accurate description. When the Spirit inspires the writers of the Bible to record the event, how do you think they might have responded?
From what little I know of the Gospels, they were written in the first century by different people in different places and at different times. I believe Mark’s version came out first followed by Matthew’s and Luke’s then John’s. In the end, the Gospel is more than a literary collection to be studied and debate; they point to how we’re to live so we can follow Christ.